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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e71b78a1dsm3584086f8f.24.2026.10.30.07.59.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Oct 2026 07:59:12 -0700 (PDT) From: David Carlier To: Jyan Chou , Yu-Chun Lin Cc: Mark Brown , linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, David Carlier , Sashiko Subject: [PATCH] spi: rtk-nor: Limit exec_op writes to one byte per operation Date: Fri, 30 Oct 2026 14:59:06 +0000 Message-ID: <20261030145909.285144-1-devnexen@gmail.com> X-Mailer: git-send-email 2.55.0 X-Mailing-List: linux-spi@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit rtk_spi_do_write_and_cmds() issues a single writeb() to the data window, so only the first byte of an addressed write reaches the flash, yet exec_op reports success for the whole buffer. spi-nor hits this when writing without a dirmap descriptor, e.g. for OTP security registers. Such ops cannot be rejected in supports_op, since spi-nor probes page program support with an addressed two byte write. Clamp them to one byte in adjust_op_size instead, so spi-nor loops over the buffer. Fixes: aca8cbecdd2e ("spi: spi-mem: Add Realtek SPI NOR flash controller driver") Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260930071125.529791F000FF@smtp.kernel.org/ Signed-off-by: David Carlier --- drivers/spi/spi-rtk-nor.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/spi/spi-rtk-nor.c b/drivers/spi/spi-rtk-nor.c index 75856c31d2e6..55ea7c371854 100644 --- a/drivers/spi/spi-rtk-nor.c +++ b/drivers/spi/spi-rtk-nor.c @@ -357,6 +357,18 @@ static bool rtk_spi_supports_op(struct spi_mem *mem, return spi_mem_default_supports_op(mem, op); } +static int rtk_spi_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op) +{ + /* + * A write through exec_op is a single access to the data window, + * which programs one byte. Let the caller split longer writes. + */ + if (op->data.dir == SPI_MEM_DATA_OUT && op->addr.nbytes) + op->data.nbytes = min(op->data.nbytes, 1U); + + return 0; +} + static int rtk_spi_dirmap_create(struct spi_mem_dirmap_desc *desc) { const struct spi_mem_op *op = desc->info.op_tmpl; @@ -449,6 +461,7 @@ static const struct spi_controller_mem_ops rtk_spi_mem_ops = { .dirmap_create = rtk_spi_dirmap_create, .dirmap_read = rtk_spi_dirmap_read, .dirmap_write = rtk_spi_dirmap_write, + .adjust_op_size = rtk_spi_adjust_op_size, }; static int rtk_spi_probe(struct platform_device *pdev) -- 2.55.0